Process for flattening glass-ceramic substrates

Claim 1

A method of forming a glass-ceramic composite structure with a copper based conductor pattern embedded therein comprising: A. forming at least one green sheet comprised of a thermoplast organic binder having dispersed therein particles of a crystallizable glass having a crystallizing temperature below the melting point of copper; B. forming on a surface of a first said green sheet a pattern of a copper based conductor forming composition; C. superimposing a second said green sheet on said surface of said first sheet to sandwich said pattern therebetween; D. laminating said sheets together; E. heating said laminate in an ambient of hydrogen and H 2 O in a ratio of H 2 /H 2 O in the range of about 10 -4 to about 10 -6 .5 to a burn-out temperature in the range between the anneal and softening points of said glass, and maintained thereat for sufficient time to sinter said particles and to decompose and eliminate said binder; F. substituting an inert gas for said ambient; G. further heating said laminate to a range between the coalescent and crystallization temperatures of said glass to partially coalesce said glass of said laminate; H. interrupting the last said heating to superimpose a coextensive inert non-adherent removable light weight planar platen on said laminate, with said platen having a weight in the range below an upper level causing extrusion of said laminate during firing or restricting lateral shrinkage of said laminate and at least at a lower level preventing vertical movement of said laminate during firing; I. further heating said laminate and superimposed platen, under sole pressure of said platen, through the coalescing temperatures of said glass to the crystallization temperature thereof to convert said glass into a glass-ceramic structure and; J. removing said platen from said glass-ceramic structure.

Claim 2

A method of forming a glass-ceramic composite structure with a copper based conductor pattern embedded therein comprising: A. forming at least one green sheet comprised of a thermoplast organic binder having dispersed therein particles of a crystallizable glass having a crystallizing temperature below the melting point of copper; B. forming on a surface of a first said green sheet a pattern of a copper based conductor forming composition; C. superimposing a second said green sheet on said surface of said first sheet to sandwich said pattern therebetween; D. laminating said sheets together; E. heating said laminate in an ambient of hydrogen and H 2 O in a ratio of H 2 /H 2 O in the range of about 10 -4 to about 10 -6 .5 to a burn-out temperature in the range between the anneal and softening points of said glass, and maintained thereat for sufficient time to sinter said particles and to decompose and eliminate said binder; F. substituting an inert gas for said ambient; G. further heating said laminate to a range between the coalescent and crystallization temperatures of said glass to partially coalesce said glass of said laminate; H. interrupting the last said heating to superimpose a coextensive inert non-adherent removable light weight planar platen on said laminate, with said platen having a weight in the range below an upper level causing extrusion of said laminate during firing or restricting lateral shrinkage of said laminate and at least at a lower level preventing vertical movement of said laminate during firing; I. further heating said laminate and superimposed platen, under sole pressure of said platen, through the coalescing temperatures of said glass to the crystallization temperature thereof to convert said glass into a glass-ceramic structure and; J. removing said platen from said glass-ceramic structure.